{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T16:13:18Z","timestamp":1790957598873,"version":"4.1.0"},"reference-count":44,"publisher":"Public Library of Science (PLoS)","issue":"5","license":[{"start":{"date-parts":[[2024,5,28]],"date-time":"2024-05-28T00:00:00Z","timestamp":1716854400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:sec id=\"sec001\">\n<jats:title>Background<\/jats:title>\n<jats:p>Patellofemoral pain (PFP) is a common knee complaint affecting diverse populations both acutely and chronically. Quadriceps muscle weakness is one possible aetiology, but current devices for measuring muscle strength (isokinetic dynamometer [ID] and hand-held dynamometers [HHD]) are frequently too expensive (e.g., ID) or lack reliability (e.g., HHD) for practitioners, especially in under-resourced settings. There is a need to evaluate a low-cost device to manage rehabilitation of people with PFP.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec002\">\n<jats:title>Methods<\/jats:title>\n<jats:p>Isometric quadriceps strength of participants aged 18\u201335 years (total [n = 33], control group [n = 17] and PFP group [n = 16]) were evaluated on an isokinetic dynamometer and a commercially available strain gauge at baseline and after an 8-week non-standardised intervention.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec003\">\n<jats:title>Results<\/jats:title>\n<jats:p>The strain gauge showed high absolute and relative reliability (intraclass correlation coefficient = 0.89\u20130.99; typical error of measurement = 3.9\u201310.4%). Clinically meaningful difference scores (12.2\u201345 Nm) were greater than the typical error of measurement, implying sufficient sensitivity of the strain gauge to measure true changes in isometric quadricep strength. Strong to very strong correlations were evident between the strain gauge and isokinetic dynamometer torque measurements (r = 0.88\u20130.90, SEE = 0.05\u20130.07 Nm), but slope values (\u03b2 = 0.65\u20130.77) indicated that torque from the strain gauge was lower than that obtained from the isokinetic dynamometer. An average systematic bias of 16.3\u201328.8 Nm was evident in favour of the isokinetic dynamometer, with no statistically significant between-group differences apparent between baseline and follow-up testing.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec004\">\n<jats:title>Conclusion<\/jats:title>\n<jats:p>The present commercially available strain gauge is reliable and sensitive enough to detect clinically meaningful differences in quadriceps strength of both healthy individuals and those with PFP. However, the strain gauge lacks validity and therefore cannot replace isokinetic dynamometry. Given the low cost and excellent reliability, the strain gauge can be a valuable tool to assess quadriceps muscle deficits and track rehabilitation progress in people with PFP.<\/jats:p>\n<\/jats:sec>","DOI":"10.1371\/journal.pone.0298570","type":"journal-article","created":{"date-parts":[[2024,5,28]],"date-time":"2024-05-28T18:20:11Z","timestamp":1716920411000},"page":"e0298570","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":4,"title":["Assessing quadriceps strength in patellofemoral pain patients: A study on the reliability and validity of a low-cost strain-gauge for clinical practice"],"prefix":"10.1371","volume":"19","author":[{"given":"Germari","family":"Deysel","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mariaan","family":"van Aswegen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2237-7549","authenticated-orcid":true,"given":"Mark","family":"Kramer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2024,5,28]]},"reference":[{"issue":"14","key":"pone.0298570.ref001","doi-asserted-by":"crossref","first-page":"839","DOI":"10.1136\/bjsports-2016-096384","article-title":"2016 Patellofemoral pain consensus statement from the 4th International Patellofemoral Pain Research Retreat, Manchester. Part 1: Terminology, definitions, clinical examination, natural history, patellofemoral osteoarthritis and patient-reported outcome measures","volume":"50","author":"KM Crossley","year":"2016","journal-title":"Br J Sports Med"},{"issue":"1","key":"pone.0298570.ref002","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1123\/jsr.2013-0101","article-title":"Sport specialization\u2019s association with an increased risk of developing anterior knee pain in adolescent female athletes","volume":"24","author":"R Hall","year":"2015","journal-title":"J Sport Rehabil"},{"issue":"1","key":"pone.0298570.ref003","doi-asserted-by":"crossref","first-page":"e237","DOI":"10.1186\/s12891-016-1097-5","article-title":"A questionnaire to identify patellofemoral pain in the community: An exploration of measurement properties","volume":"17","author":"P Dey","year":"2016","journal-title":"BMC Musculoskeletal Disorders"},{"issue":"4","key":"pone.0298570.ref004","first-page":"396","article-title":"Prevalence of anterior knee pain in 18\u201335 year-old females","volume":"7","author":"JR Roush","year":"2012","journal-title":"J Sports Phys Ther"},{"issue":"1","key":"pone.0298570.ref005","doi-asserted-by":"crossref","first-page":"e452","DOI":"10.4102\/sajp.v74i1.452","article-title":"Anterior knee pain and its intrinsic risk factors among runners in under-resourced communities in Ekurhuleni, Gauteng.","volume":"74","author":"SH Kunene","year":"2018","journal-title":"S Afr J Physiother."},{"key":"pone.0298570.ref006","doi-asserted-by":"crossref","first-page":"96","DOI":"10.1016\/j.ptsp.2018.06.006","article-title":"Quality of life in individuals with patellofemoral pain: A systematic review including meta-analysis.","volume":"33","author":"SL Coburn","year":"2018","journal-title":"Physical Therapy in Sport"},{"issue":"4","key":"pone.0298570.ref007","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1136\/bjsports-2012-091696","article-title":"Prognostic factors for patellofemoral pain: a multicentre observational analysis.","volume":"47","author":"NJ Collins","year":"2013","journal-title":"Br J Sports Med"},{"issue":"4","key":"pone.0298570.ref008","first-page":"678","article-title":"The quality of life of patients with patellofemoral pain\u2014a systematic review.","volume":"86","author":"L Reijnders","year":"2020","journal-title":"Acta Orthop Belg"},{"issue":"4","key":"pone.0298570.ref009","doi-asserted-by":"crossref","first-page":"568","DOI":"10.1111\/j.1600-0838.2009.00980.x","article-title":"Cost-utility of exercise therapy in adolescents and young adults suffering from the patellofemoral pain syndrome","volume":"20","author":"SS Tan","year":"2010","journal-title":"Scand J Med Sci Sports"},{"issue":"1","key":"pone.0298570.ref010","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1097\/01241398-199801000-00021","article-title":"Natural History of Anterior Knee Pain: A 14- to 20-Year Follow-up of Nonoperative Management [Abstract].","volume":"18","author":"G Nimon","year":"1998","journal-title":"Journal of Pediatric Orthopaedics"},{"issue":"1","key":"pone.0298570.ref011","doi-asserted-by":"crossref","first-page":"e201","DOI":"10.1186\/1471-2474-11-201","article-title":"Anterior knee pain in younger adults as a precursor to subsequent patellofemoral osteoarthritis: a systematic review.","volume":"11","author":"MJ Thomas","year":"2010","journal-title":"BMC Musculoskelet Disord"},{"issue":"5","key":"pone.0298570.ref012","doi-asserted-by":"crossref","first-page":"666","DOI":"10.1016\/j.semarthrit.2017.09.009","article-title":"International patellofemoral osteoarthritis consortium: Consensus statement on the diagnosis, burden, outcome measures, prognosis, risk factors and treatment","volume":"47","author":"M Van Middelkoop","year":"2018","journal-title":"Semin Arthritis Rheum"},{"issue":"11","key":"pone.0298570.ref013","doi-asserted-by":"crossref","first-page":"2108","DOI":"10.1177\/0363546509337934","article-title":"A Prospective Investigation of Biomechanical Risk Factors for Patellofemoral Pain Syndrome The Joint Undertaking to Monitor and Prevent ACL Injury (JUMP-ACL) Cohort.","volume":"37","author":"MC Boling","year":"2009","journal-title":"Am J Sports Med"},{"issue":"1","key":"pone.0298570.ref014","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1002\/art.24182","article-title":"Quadriceps Strength and the Risk of Cartilage Loss and Symptom Progression in Knee Osteoarthritis","volume":"60","author":"S Amin","year":"2009","journal-title":"Arthritis Rheum"},{"issue":"9","key":"pone.0298570.ref015","doi-asserted-by":"crossref","first-page":"CPG1","DOI":"10.2519\/jospt.2019.0302","article-title":"Patellofemoral pain.","volume":"49","author":"RW Willy","year":"2019","journal-title":"J Orthop Sports Phys Ther"},{"issue":"1","key":"pone.0298570.ref016","first-page":"e47","article-title":"Isometric Strength Database for Muscle Maximal Voluntary Endurance Field Tests: Normative Data.","volume":"7","author":"F Janik","year":"2021","journal-title":"Sports Med"},{"issue":"5","key":"pone.0298570.ref017","doi-asserted-by":"crossref","first-page":"472","DOI":"10.1016\/j.pmrj.2010.10.025","article-title":"Hand-held Dynamometry Correlation With the Gold Standard Isokinetic Dynamometry: A Systematic Review.","volume":"3","author":"T Stark","year":"2011","journal-title":"PM&R"},{"issue":"1","key":"pone.0298570.ref018","doi-asserted-by":"crossref","first-page":"359","DOI":"10.1515\/med-2017-0052","article-title":"Absolute reliability and concurrent validity of hand held dynamometry and isokinetic dynamometry in the hip, knee and ankle joint: Systematic review and meta-analysis.","volume":"12","author":"C Chamorro","year":"2017","journal-title":"Open Med"},{"issue":"6","key":"pone.0298570.ref019","doi-asserted-by":"crossref","first-page":"296","DOI":"10.2519\/jospt.1994.20.6.296","article-title":"Assessment of quadriceps muscle performance by a hand-held dynamometer and an isokinetic dynamometer.","volume":"20","author":"VL Deones","year":"1994","journal-title":"JOSPT"},{"key":"pone.0298570.ref020","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1007\/s42978-022-00215-8","article-title":"Reliability and Utility of Load\u2011Cell Derived Force\u2013Time Variables Collected During a Constrained and Unconstrained Isometric Knee Extension Task on a Plinth.","volume":"6","author":"C Juneau","year":"2024","journal-title":"Journal of Science in Sport and Exercise"},{"key":"pone.0298570.ref021","volume-title":"Research methods, design and analysis.","author":"LB Christensen","year":"2015","edition":"12"},{"issue":"2","key":"pone.0298570.ref022","first-page":"175","article-title":"Statistics textbooks in the social.","volume":"39","author":"F Faul","year":"2007","journal-title":"Behavior Research Methods"},{"issue":"2","key":"pone.0298570.ref023","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1016\/j.math.2011.07.002","article-title":"Systematic review Evaluation of outcome measures for use in clinical practice for adults with musculoskeletal conditions of the knee: A systematic review.","volume":"17","author":"TE Howe","year":"2012","journal-title":"Man Ther"},{"issue":"3","key":"pone.0298570.ref024","doi-asserted-by":"crossref","first-page":"136","DOI":"10.2519\/jospt.2005.35.3.136","article-title":"Reliability and responsiveness of the lower extremity functional scale and the anterior knee pain scale in patients with anterior knee pain","volume":"35","author":"CJ Watson","year":"2005","journal-title":"J Orthop Sports Phys Ther"},{"issue":"3","key":"pone.0298570.ref025","doi-asserted-by":"crossref","first-page":"129","DOI":"10.5958\/0973-5674.2015.00110.0","article-title":"Quadriceps Femoris Strength Training: effect of Neuromuscular Electrical Stimulation Vs Isometric Exercise in Osteoarthritis of Knee","volume":"9","author":"S. Hasan","year":"2015","journal-title":"Indian J Physiother Occup Therapy"},{"key":"pone.0298570.ref026","doi-asserted-by":"crossref","DOI":"10.1115\/DMD2018-6848","volume-title":"Isometric quadriceps strength test device to improve the reliability of handheld dynamometry in patient with anterior cruciate ligament injury","author":"S McNamara","year":"2018"},{"key":"pone.0298570.ref027","article-title":"Serotonergic neurons of the nucleus raphe Magnus in the control of nociceptive transmission in the dorsal horn of the spinal cord: an optogenetic study in different pathophysiological contexts.","author":"Bordeaux","year":"2019","journal-title":"Nouvelle-Aquitaine, France]: University of"},{"issue":"2","key":"pone.0298570.ref028","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1016\/j.jcm.2016.02.012","article-title":"A Guideline of Selecting and Reporting Intraclass Correlation Coefficients for Reliability Research.","volume":"15","author":"TK Koo","year":"2016","journal-title":"J Chiropr Med"},{"issue":"11","key":"pone.0298570.ref029","doi-asserted-by":"crossref","first-page":"1931","DOI":"10.1088\/0967-3334\/33\/11\/1931","article-title":"Test\u2013retest reliability and minimal detectable change of repeated sit-to-stand analysis using one body fixed sensor in geriatric patients.","volume":"33","author":"M Schwenk","year":"2012","journal-title":"Physiol Meas"},{"issue":"1","key":"pone.0298570.ref030","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1249\/MSS.0b013e31818cb278","article-title":"Progressive statistics for studies in sports medicine and exercise science","volume":"41","author":"WG Hopkins","year":"2009","journal-title":"Med Sci Sports Exerc"},{"issue":"5","key":"pone.0298570.ref031","doi-asserted-by":"crossref","first-page":"1763","DOI":"10.1213\/ANE.0000000000002864","article-title":"Correlation Coefficients: Appropriate Use and Interpretation.","volume":"126","author":"P Schober","year":"2018","journal-title":"Anesthesia & Analgesia"},{"issue":"2","key":"pone.0298570.ref032","doi-asserted-by":"crossref","first-page":"141","DOI":"10.11613\/BM.2015.015","article-title":"Understanding Bland Altman analysis","volume":"25","author":"D. Giavarina","year":"2015","journal-title":"Biochem Med (Zagreb)"},{"key":"pone.0298570.ref033","article-title":"rsquaredacademy\/olsrr","author":"A. Hebbali","year":"2023","journal-title":"Rsquared Academy"},{"key":"pone.0298570.ref034","unstructured":"R Core Team. R: The R Project for Statistical Computing [Internet]. Vienna, Austria: R Foundation for Statistical Computing; [cited 2024 Jan 8]. Available from: https:\/\/www.r-project.org\/"},{"issue":"9","key":"pone.0298570.ref035","doi-asserted-by":"crossref","first-page":"809","DOI":"10.4085\/1062-6050-52.6.04","article-title":"Reliability and Validity of the Belt-Stabilized Handheld Dynamometer in Hip-and Knee-Strength Tests.","volume":"52","author":"J Martins","year":"2017","journal-title":"J Athl Train"},{"issue":"1","key":"pone.0298570.ref036","doi-asserted-by":"crossref","first-page":"22","DOI":"10.4085\/1062-6050-51.1.12","article-title":"Knee-Extension Torque Variability and Subjective Knee Function in Patients with a History of Anterior Cruciate Ligament Reconstruction.","volume":"51","author":"J Goetschius","year":"2016","journal-title":"J Athl Train."},{"issue":"6","key":"pone.0298570.ref037","doi-asserted-by":"crossref","first-page":"1099","DOI":"10.1177\/0363546508331135","article-title":"Delayed vastus medialis obliquus to vastus lateralis onset timing contributes to the development of patellofemoral pain in previously healthy men: a prospective study [Abstract].","volume":"37","author":"D Van Tiggelen","year":"2009","journal-title":"Am J Sports Med."},{"issue":"3","key":"pone.0298570.ref038","doi-asserted-by":"crossref","first-page":"590","DOI":"10.1177\/0363546510384233","article-title":"Patellar maltracking correlates with vastus medialis activation delay in patellofemoral pain patients","volume":"39","author":"S Pal","year":"2011","journal-title":"Am J Sports Med"},{"issue":"4","key":"pone.0298570.ref039","doi-asserted-by":"crossref","first-page":"227","DOI":"10.5812\/asjsm.34747","article-title":"Effect of Eccentric Isotonic Quadriceps Muscle Exercises on Patellofemoral Pain Syndrome: An Exploratory Pilot Study.","volume":"2","author":"C Eapen","year":"2011","journal-title":"Asian J Sports Med"},{"issue":"4","key":"pone.0298570.ref040","doi-asserted-by":"crossref","first-page":"202","DOI":"10.6061\/clinics\/2017(04)02","article-title":"Effects of Motor Learning on Clinical Isokinetic Test Performance in Knee Osteoarthritis Patients.","volume":"72","author":"JM Rodrigues-da-Silva","year":"2017","journal-title":"Clinics (Sao Paulo)"},{"key":"pone.0298570.ref041","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1186\/1471-2474-10-31","article-title":"Hand-held dynamometry in patients with haematological malignancies: Measurement error in the clinical assessment of knee extension strength.","volume":"10","author":"RH Knols","year":"2009","journal-title":"BMC Musculoskelet Disord"},{"issue":"1","key":"pone.0298570.ref042","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/j.ptsp.2014.04.004","article-title":"Inter-machine reliability of the Biodex and Cybex isokinetic dynamometers for knee flexor\/extensor isometric, concentric and eccentric tests.","volume":"16","author":"JB de Araujo Ribeiro Alvares","year":"2015","journal-title":"Physical Therapy in Sport"},{"issue":"2","key":"pone.0298570.ref043","doi-asserted-by":"crossref","first-page":"120","DOI":"10.1589\/jpts.32.120","article-title":"Validity and reliability of isometric knee extension muscle strength measurements using a belt-stabilized hand-held dynamometer: a comparison with the measurement using an isokinetic dynamometer in a sitting posture","volume":"32","author":"M Hirano","year":"2020","journal-title":"Journal of Physical Therapy Science"},{"key":"pone.0298570.ref044","article-title":"The Validity of a Portable Strain-Gauge Apparatus Versus a Commercial Isokinetic Dynamometer for Evaluating Knee Extension Kinetics.","author":"D Oranchuk","year":"2024","journal-title":"International Journal of Sports Physical Therapy"}],"container-title":["PLOS ONE"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0298570","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,5,28]],"date-time":"2024-05-28T18:20:35Z","timestamp":1716920435000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0298570"}},"subtitle":[],"editor":[{"given":"Theodoros M.","family":"Bampouras","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2024,5,28]]},"references-count":44,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2024,5,28]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0298570","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,5,28]]}}}